Sometimes I watch my clients in a dressage test and see restricted movement in only one lateral movement. For instance, if the half pass going to the right looks good, but then half pass going to the left is poor, I am given a clue as to where to feel in the next body work session: there is likely a knot in the right external oblique attachment. The external oblique attaches to the hip bone (or tuber coxae) and part of its’ job is to flex the trunk laterally. This a stress point that I find and treat often in dressage and event horses.
Another important note!: When a horse has tied up and is unable to move the hind legs, he can often be given great relief by releasing the external oblique stress point.